Such is a practice of the governor's office to protect North Dakota's gubernatorial line of succession. Governor's spokesman Mike Nowatzki said it's not a policy, but "a best practice to ensure continuity of government."

Nowatzki said the Hoeven and Dalrymple administrations both followed the practice. Former Gov. Ed Schafer said he never flew or even drove with the lieutenant governor. He said the practice was "a natural thing" for him, coming from a business background and keeping a corporation's president and vice president from flying together.

"The theory is one can step in for the other," Schafer said. "If you both go down in the car crash, that doesn't work."

Former Lt. Gov. Lloyd Omdahl, who served from 1987-92, said it "was an understanding" between him and then-Gov. George Sinner to never fly together, though he added they did do so once.

"Well, governors do get killed in plane crashes, and ... I guess it's probably a good rule," Omdahl said.

South Dakota Gov. George Mickelson died in a plane crash in 1993 near Dubuque, Iowa. Though South Dakota's lieutenant governor was not aboard the plane, Nowatzki said the tragedy could have contributed to North Dakota's practice, but its origins aren't clear.

As for who arrives at a destination in what manner, Nowatzki said it's a case-by-case basis depending on circumstances of where Burgum and Sanford are leaving from and where their meetings are. He also noted they have "very different schedules."

For one shared appearance, Nowatzki said Sanford drove to Watford City, where he has a home, the night before the grand opening last year of the McKenzie County Law Enforcement Center. Burgum flew to Watford City the day of the event to offer comments with other state and local officials at the ceremony.

"Here's the reality: That's why you have a lieutenant governor," Schafer said. "The theory of a lieutenant governor is to have someone who is there, prepared and engaged to take over if need be, so anything you do to keep the safety of the two individuals separate, I think, is important."

North Dakota's constitution establishes the secretary of state as second in the line of succession for the governor's seat. Two lieutenant governors have succeeded a governor due to death in office, most recently in 1928.